I had to write a simple desktop app for internal use. Nothing super complicated, but it did require some low-level system stuff that I have zero experience with. Had Codex code up something that worked perfectly. In total, spent a couple days making sure everything did work as expected and nothing stupid was going on. Would've taken me at least a week to research the stuff I didn't know, get a decent UI in place, validation, etc.
Submitted for code review and of course someone got bent out of shape because the agent used Array instead of List...
Arrays vs lists is one of the great "Bike Shed" ( Law of triviality - Wikipedia ) traps of code reviews. Best way to handle those discussions (besides just changing to whatever data structure is appropriate, which is suprisingly array more often than people think...) is to profile the difference on an appropriately sized memory space with considerations of how often it re-allocates and how often the structure is traversed. Unless you're chucking a lot of data in each element it's really hard to beat arrays.
I haven't used Codex, but using AI to jumpstart a project in unfamiliar libraries or languages is a no brainer these days.